First steps - first problems

Hello everyone,
I'm new here (but not so new to WoW) and I got few problems with launching the game.

CATA
I've downloaded everything from your page, but when i want to extract i got problem around 80% and it's called *few numbers* error (I think it can't found some archives)

MOP
Here everything works fine, but game never launched - all i get is this error "Data/enGB/wow-update-enGB-18273.MPQ: World of Warcraft can’t make a required change to an archive file. Be sure you have write permission for the World of Warcraft folder or try running the game in administrator mode." I've tried admin mode etc. but nothing changed.

WOTLK
I'm downloading it right now so wish me no issues ;)

So the question is - is it my computer's fault or your client? Or both? I have no idea how to fix that and honestly I'm confused that I can't launch both versions properly... I've played lot of time Wotlk and has never such an issues with launching the game - just download, change realmlist and enjoy - and here I don't know is it my fault or broken client.

Thanks for answers and help!

There's definitely something wrong with your pc, I played and downloaded all those from molte-Uhm Warmane site and it worked fine. I suggest you reinstall your OS, there's for example Win7 Lite version which is absolutely awesome, also there's new fast way of deleting your old OS using partition programs, it takes about 5 mins to reinstall and format.

about Cata just download it again.

About MoP:
1) Restart your PC
2) close your Torrent client and move your WoW folder away from your Torrent's download destination
3) now right click on WoW folder> Properties> remove "read-only"